1. Technical Field
The present invention relates to a method of transmitting data by using a wireless local area network (WLAN) in a wireless communication system, and more particularly, to a method of transmitting data by using user's context information sensed by a user equipment (UE).
2. Related Art
Since a wireless local area network (WLAN) is an untrusted network in general, a long term evolution (LTE) network interworks with the WLAN by using an S2b interface for interworking with an “untrusted non-3GPP access network”.
In this case, in order to ensure reliable interworking, enhanced packet data gateway (ePDG) and 3GPP authentication authorization accounting (AAA) (3A) are added in addition to the existing evolved packet system (EPS) entity. The ePDG generates an authentication and tunnel for a user equipment (UE), and a WLAN is located between the ePDG and the UE.
The conventional technique makes a WLAN having a security problem a ‘trust’ network, so that the UE can receive a service while maintaining a security level of an LTE network even if communication is performed through the WLAN. Accordingly, interworking is possible when an access point (AP) of the WLAN accessed by the UE is directly connected with the ePDG. That is, interworking between the LTE network and the WLAN is possible only for a WLAN AP installed by a vendor who operates the LTE network. However, a current network context is a context in which the number of WLAN APs installed by an ordinary user is greater than the number of WLANs installed by a communication vendor. Therefore, there is a need for a traffic transmission scheme using the WLAN AP installed by the ordinary user.
If a congestion occurs in the LTE network, conventionally, an effect of offloading a traffic of the LTE network can be acquired only when a UE autonomously accesses a WLAN AP while experiencing an inconvenience of receiving a service according to the network congestion. Since a deterioration of service quality is experienced by a user in this process, there is a need for a method capable of increasing a radio duration transfer rate of the UE before the service quality deterioration occurs based on the congestion in the LTE network in order to ensure quality of experience (QoE) However, the conventional system has no method capable of determining whether the UE is in a context in which an access to the WLAN is possible, and there is no proposed method for generating a WLAN connection of the UE under the control of a network.
Meanwhile, a base station performs scheduling to effectively use a limited frequency resource. A representative method thereof includes a round robin scheme, a max C/I scheme, a proportional factor scheme, etc. The round robin scheme is a scheme in which resources are allocated by selecting users sequentially to ensure fairness preferentially. The max C/I scheme is a scheme in which a frequency is allocated preferentially to a user having a best channel state to maximize a total throughput of a system. The proportional factor scheme is a scheme in which a frequency is allocated on the basis of a channel state of a user and an average through of a service received up to now to simultaneously consider fairness and process ability.
The mobile communication system manages a current frequency resource on the basis of user request service information in order to control quality of service (QoS) of communication. Since a QoS requirement differs for each service, QoE may differ depending on a service type in use even if the same QoS level is ensured. Most of the conventional scheduling methods considering the service type allocate a frequency resource preferentially to a user who uses a real-time service (e.g., a streaming video or an online game). This is because a delay occurrence of the real-time service leads to a loss of information to be transmitted soon on a real-time basis, thereby causing a significant decrease in the QoE.
The conventional scheduling method does not consider an environment in which a UE is used. In this case, a purpose of scheduling may be limited to maximize a system-centered throughput or to ensure fairness, and QoE may not be individually ensured. More specifically, in the conventional scheduling method, there is a frequently occurring case in which a user expected to have a short data usage time cannot be distinguished, and thus a service cannot be provided preferentially to such a user. Since the users having the short data usage time sensitively respond to a slight increase in a delay, total QoE is rapidly decreased when a delay of such users is increased. Accordingly, there is a need for a scheduling scheme capable of recognizing context information of the users in a system and allocating a frequency resource preferentially to the users having the short data usage time.